JSP代码 MVC编程开发实例

我之前一直搞不明白JAVABEAN在MVC中到底充当一个什么角色。现在来看一个实例

定义一个JAVABEAN
package com.bean;
public class User {
    private String userName;
    private String userPwd;
    public String getUserName() {
        return userName;
    }

    public void setUserName(String userName) {
        this.userName = userName;
    }

    public String getUserPwd() {
        return userPwd;
    }

    public void setUserPwd(String userPwd) {
        this.userPwd = userPwd;
    }
}

JAVABEAN的作用：是一个PO对象之前我以为是VO对象。搞错了！

恩我们可以这样来理解JAVABEAN的作用其实就是用来传递数据的一个东西。在我们这次PHPCMS项目中相当于一个结果集的传输。控制器接收到一个来自M层的数据之后如何传递到视图层作渲染处理。可以依据这样的方式。

再来看我们的Action类
package com.dao;
import java.sql.*;
import com.bean.User;
public class DAO {
    Connection conn = null;
    Statement stmt = null;
    ResultSet rs = null;
    PreparedStatement pstmt = null
    public DAO(){
        try {
            Class.forName("com.mysql.jdbc.Driver");
            conn = getConnection();
        } catch (ClassNotFoundException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }

    public Connection getConnection(){
        String url = "jdbc:mysql://localhost:3306/person";
        String user = "root";
        String password = "123456";
        try {
            conn = DriverManager.getConnection(url, user, password);
        } catch (SQLException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        return conn;
    }

    public int addPerson(User user){
        int flag = 0;
        String sql = "insert into user(user_name,user_pwd) values(?,?)";
        try {
            pstmt = conn.prepareStatement(sql);
            pstmt.setString(1, user.getUserName());
            pstmt.setString(2, user.getUserPwd());
            flag = pstmt.executeUpdate();

        } catch (SQLException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        return flag;
    }

    public ResultSet showPerson(){
        String sql = "select * from user";
        try {
            pstmt = conn.prepareStatement(sql);
            rs = pstmt.executeQuery();
        } catch (SQLException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        return rs;
    }

    public void close(){
        try {
            if(rs!=null)rs.close();
            if(pstmt!=null)pstmt.close();
            if(conn!=null)conn.close();

        } catch (SQLException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }
}

这个类把数据库连接操作也放在这里了。其实是不正确的处理方式。正确的方式应当是将数据库层单独写到一个CLASS类里面去。但这里面我们来看一下：

public int addPerson(User user){
        int flag = 0;
        String sql = "insert into user(user_name,user_pwd) values(?,?)";
        try {
            pstmt = conn.prepareStatement(sql);
            pstmt.setString(1, user.getUserName());
            pstmt.setString(2, user.getUserPwd());
            flag = pstmt.executeUpdate();
        } catch (SQLException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        return flag;
    }

这个DAO对象它的作用是接收来自JAVABEAN层的数据。

再看是如何SET值到这个BEAN的

package com.servlet;
 import java.io.IOException;
 import java.io.PrintWriter;
 import javax.servlet.ServletException;
 import javax.servlet.http.HttpServlet;
 import javax.servlet.http.HttpServletRequest;
 import javax.servlet.http.HttpServletResponse;
 import com.bean.User;
 import com.dao.DAO;
 public class AddUser extends HttpServlet {
 public void doGet(HttpServletRequest request, HttpServletResponse response)
        throws ServletException, IOException {
        String userName = request.getParameter("userName");
        String userPwd = request.getParameter("userPwd");
        User user = new User();
        user.setUserName(userName);//依据的是SET与GET方式了吧！！！！
        user.setUserPwd(userPwd);
        DAO dao = new DAO

补充：Web开发 , Jsp ,